Pregnancy Outcomes in the Omalizumab Pregnancy Registry and a Disease-matched Comparator Cohort

Abstract Background The EXPECT pregnancy registry was a prospective observational study established in 2006 to evaluate perinatal outcomes in pregnant women exposed to omalizumab and their infants. Objective This analysis compares EXPECT outcomes with those from a disease-matched population of pregnant women not treated with omalizumab. Data from a substudy of platelet counts among newborns are also presented. Methods EXPECT enrolled 250 women with asthma exposed to omalizumab during pregnancy. The disease-matched external comparator cohort of women with moderate to severe asthma (n=1,153), termed the Quebec External Comparator Cohort, was created using data from healthcare databases in Quebec, Canada. Outcome estimates were age-adjusted based on the maternal age distribution of EXPECT. Results Among singleton infants in EXPECT, the prevalence of major congenital anomalies was 8.1%, similar to 8.9% in the Quebec External Comparator Cohort. In EXPECT, 99.1% of pregnancies resulted in live birth, similar to 99.3% in the Quebec External Comparator Cohort. Premature birth was identified in 15.0% of EXPECT infants and 11.3% in the Quebec External Comparator Cohort. Small for gestational age was identified in 9.7% of EXPECT infants and 15.8% in the Quebec External Comparator Cohort. Conclusion There was no evidence of an increased risk of major congenital anomalies among pregnant women exposed to omalizumab compared to a disease-matched unexposed cohort. Given the observational nature of this registry, however, an absence of increased risk with omalizumab cannot be definitively established.